Emergency and uniterruptible lighting systems have heretofore been proposed, illustrative of which are those shown and described in co-pending U.S. patent application Ser. No. 08/063,359 filed by M. Larry Edwards and W. Joe Watson on May 17, 1993 now U.S. Pat. No. 5,471,114 granted Nov. 28, 1995. In accordance with such prior proposals, one or more lights or banks of lights are controlled selectively such that when in a fail-safe emergency mode, the light(s) continue to be energized for a substantial period of time after normal sources of electric power are interrupted. According to the foregoing proposal, a battery is continuously connected to one or more light ballasts such that as alternating current from a commercial source is supplied and rectified, the battery alternately receives and supplies current during each cycle thus retaining its charge so long as power is being received from the mains. When power from the mains is interrupted, the battery continues to supply power to the lights thus maintaining their luminescence without the necessity for switching.
Other proposals have been made for switching between power from commercial sources and the like to battery power for lighting systems during power outages. Still other proposals have been made for selective energization of one of a pair of lights when the normal source of power is interrupted. Such proposal is set forth in U.S. Pat. No. 4,727,291 granted to Joseph P. Bavaro on Feb. 23, 1988. Yet other proposals have been made for emergency lighting systems with routine self diagnosis. Such are illustrated in U.S. Pat. No. 4,945,280 granted to Gian P. Beghelli on Jul. 31, 1990. Although these proposals include a variety of systems and types of operation, there has continued to be a need for a modular fail-safe lighting system in which provision is made for selection of any of a wide variety of modes of operation when the normal source of power is interrupted and in which such selection can be made simply and easily in the field.